Symptoms
After you install the Microsoft Exchange Server November 2024 Security Update (SU) (Version 1 or Version 2), you might encounter issues that are related to processing calendar-related files, such as .ical or .ics attachments. You can't preview the files or add them to the calendar.
Additionally, this issue could affect the Exchange Transport service when it processes email messages that have .ical or .ics attachments. In this situation, the Transport Service restarts, email messages are sent to the poison queue, and the following exception is logged in the event log:
Microsoft.Exchange.ExchangeSystem.InvalidTimeZoneException: Time zone id already exists
Resolution
To fix this issue, install the following Hotfix updates:
